Question

Which of the following are the examples of a chemical reaction?

• A. Conversion of steam to liquid water
• B. Rusting of iron
• C. Cutting of wood
• D. Conversion of paper to paper plane

Answer 1

The correct option is B Rusting of iron

Rusting of iron is a chemical reaction. Iron reacts with oxygen in the presence of water or air moisture and gets converted to new compounds called iron (iii) oxide (rust) which has properties entirely different from that of iron or oxygen.

Moreover in other mentioned processes composition of substance remains the same and only physical state, shape etc. has changed and these changes are called physical changes.

For example:- Conversion of steam ${\text{H}}_2\text{O}$ (g) to water ${\text{H}}_2\text{O}$ (l) and it means that composition is same and only the physical state has changed.